Abstract

Sound is a medium used by humans to carry information. The existence
of this kind of medium is a pre-requisite for language. It is organized
into a code, called speech, which provides a repertoire of forms
that is shared in each language community. This code is necessary to
support the linguistic interactions that allow humans to communicate.
How then may a speech code be formed prior to the existence of linguistic
interactions?
Moreover, the human speech code is characterized by several properties:
speech is digital and compositional (vocalizations are made of units
re-used systematically in other syllables); phoneme inventories have precise
regularities as well as great diversity in human languages; all the
speakers of a language community categorize sounds in the same manner,
but each language has its own system of categorization, possibly very
different from every other. How can a speech code with these properties
form?
These are the questions we will approach in the paper. We will study
them using the method of the artificial. We will build a society of artificial
agents, and study what mechanisms may provide answers. This will not
prove directly what mechanisms were used for humans, but rather give
ideas about what kind of mechanism may have been used. This allows us
to shape the search space of possible answers, in particular by showing
what is sufficient and what is not necessary.
The mechanism we present is based on a low-level model of sensorymotor
interactions. We show that the integration of certain very simple
and non language-specific neural devices allows a population of agents
to build a speech code that has the properties mentioned above. The
originality is that it pre-supposes neither a functional pressure for communication,
nor the ability to have coordinated social interactions (they
do not play language or imitation games). It relies on the self-organizing
properties of a generic coupling between perception and production both
within agents, and on the interactions between agents.